rough idle fixed/ now whistles like a bov.

[Paralyzer]

Ok so for the longest time I have had the dreaded rpm rough idle drop when you come to a stop.I got fed up with it and decided that I would set a mission to find out why since 3 dealerships couldn't tell me and also 3 mechanic shops as well.

So I went a block over and bought some shop rags that wouldn't shred and bought a can of throttle body cleaner. I took out my airbox and pulled the throttle body out. Disconnected the idle air control sensor and started cleaning. There was a couple things I noticed, the IAC was coverded with dark gray carbon so I cleaned it out really well, and also noticed the throttle body on the inside seemed to have a seam around where the butteryfly rest when closed. So I sprayed the butterfly, and tons of black and grey residue came rolling out. The seam line was still there, so i ran my finger around it and found out it was a seam line....a seam line of carbon. Which looked like the butterfly could not close completely. So I cleaned it all out to where it was smooth.

Put everything back together, tightened all bolts and now the rough idle is gone! I still see my rpms drop to 600 but the car doesn't shake like it used to. I am now getting a whistle noise as I drive and right when it changes gears like a bov. If I could only find out what that is now.

In general though the car runs and drives so much better and the WOT pull is more responsive. Thought I would post this for you guys to know what to try if you are having the same issues.

[Chris04sxt]

Do you have a CAI? That could be the source of the whistling.

[Paralyzer]

Nope I took it off an put my stock airbox back on.

[occasional demons]

If it is just at throttle tip in, it is prolly the air going by the holes for the IAC. It closes when the throttle opens, crating a closed end tube. Kind of like blowing across a beer bottle. That's my theory, anyways.

[Purpose]

I do this once or twice a month.

[DetergentCandy]

Neat. I'll give this a try.